The present invention relates generally to facsimile transmission systems, and more particularly to a facsimile transmission system that reduces the amount of transmission time required to transmit a document.
Transmission of documents via facsimile machines is common. Although standards exist for error correction and data compression, transmission times remain considerable for large documents and those with high printing density.
Many methods have been developed for reducing the transmission time of facsimiles, such as U.S. Pat. No. 4,922,348 which discloses a method for efficiently transmitting facsimile information using commercially available facsimile devices. This method permits the telephone network to recognize communication activity between two facsimiles and provides intermediate storage capability within the telephone network to increase the transmission efficiency. While promising to reduce transmission time this method, and data compression techniques based solely on the bit map representations of information present in a document to be transmitted can only reduce the transmission time to that required to transmit the information content represented by those bit maps. Thus, inherent limits exist which dictate the extent to which transmission time for a facsimile can be reduced without reducing the information content of the transmission.
Machine interpretable forms are a developing technology that provide a methodology for encoding important information about a document on the document itself. U.S. Pat. No. 4,933,979 discloses a form sheet reading apparatus that has a means for storing form information on form sheets and means for automatically discriminating a frame line of a form sheet, which is read and detected by comparing the detected frame line with frame line information within the form information stored in the storing means. Thus, data entered within predetermined regions of the form sheet are read under reading conditions determined by the form information stored in the storing means. This permits optimization of the efficiency of an optical character reader.
The present invention is directed to the problem of developing a method and apparatus for significantly reducing the transmission time of a facsimile device, without degrading the quality of the transmitted document